OBJECTIVE. Previously, we demonstrated hyperreactive
adrenocorticotropic hormone (ACTH) release in patients with
primary fibromyalgia syndrome (primary FMS). We investigated
the pituitary release of growth hormone (GH) and prolactin
(PRL) in search of further disturbances in neuroendocrine
reactivity possibly associated with the pathophysiology of
primary FMS.

METHODS. Ten female patients with primary FMS
fulfilling the 1981 Yunus criteria and 10 matched, healthy and
sedentary controls were subjected to an insulin induced
hypoglycemia test; samples for measurement of glucose, GH and
PRL were taken at intervals.

RESULTS. Compared to the
controls, the patients with primary FMS displayed
significantly lower basal GH levels, whereas their basal PRL
levels were slightly, though significantly, higher
(respectively p = 0.021 and p = 0.041). Following
hypoglycemia, there was a marked, statistically highly
significant (p = 0.001), hyperreactivity of the GH response in
patients with primary FMS. The PRL response showed wide
interindividual variation and did not differ between patients
and controls.

CONCLUSION. Our findings indicate that
fibromyalgia, along with ACTH hyperreactivity, also exhibits a
distinct disturbance in the GH-somatomedin C axis. With regard
to PRL, the variation in individual responses limits
conclusions. The hyperreactive response patterns of GH and
ACTH previously suggest a common origin, which might be
related to a subtle glucocorticoid deficiency.